Spunbond laminate and method of making same

ABSTRACT

A spunbond nonwoven laminate has a first spunbond nonwoven layer having crimped filaments formed by a first component on an outer surface of the filaments of the first layer consisting or substantially consisting of a polyolefin and a second component consisting or substantially consisting of a plastic having a higher melting point than the polyolefin of the first component of the filaments of the first layer. A second outermost spunbond nonwoven layer on the first layer having filaments as a cover layer and formed by a first component on an outer surface of the filaments of the second layer consisting or substantially consisting of a polyolefin, and a second component consisting or substantially consisting of a plastic having a higher melting point than the polyolefin of the first component of the filaments of the second layer.

FIELD OF THE INVENTION

The invention relates to a spunbond nonwoven laminate having a pluralityof spunbond nonwoven layers one atop the other, at least two of thespunbond nonwoven layers having crimped continuous filaments orconsisting or consisting substantially of crimped continuous filaments.

The invention further relates to a method of making such a spunbondnonwoven laminate. Due to their quasi-endless length, continuousfilaments differ from staple fibers that have significantly shorterlengths of, for example, 10 mm to 60 mm.

BACKGROUND OF THE INVENTION

Spunbond nonwoven laminates of the above-described type are known fromthe prior art and from practice in various design variants. For manyapplications, nonwoven fabrics having considerable thickness and havinga high degree of softness are required. Considerable thickness isusually achieved by using crimped filaments. In particular,multicomponent or bicomponent filaments with side-by-side configurationor with eccentric core-sheath configuration are used for this. Thecharacteristics of high thickness and high softness are usuallyassociated with a relatively low strength of the nonwoven fabric. On theone hand, this applies to the tensile strength of the nonwoven fabric inthe machine direction (MD). On the other hand, this also applies inparticular to the abrasion resistance of the nonwoven surface. In thisregard, an increase in thickness and softness often adversely affectsthe abrasion properties of the nonwoven fabrics. Therefore there is aconflict of goals. So far, the solution has presented the person skilledin the art with problems. In addition to a high resistance of thenonwoven fabrics or the nonwoven fabric surface to abrasive stresses,the greatest possible opacity of the nonwoven fabrics is oftendesirable. Many of the nonwoven fabrics or nonwoven laminates known fromthe prior art also do not meet this requirement.

OBJECT OF THE INVENTION

The object of the invention is to provide a spunbond nonwoven laminateof the type described above, which is distinguished on the one hand byconsiderable thickness and a high degree of softness and on the otherhand also has optimum strength and, above all, has a high abrasionresistance or a high resistance to abrasive stress. The spunbondnonwoven laminate should also have very good opacity. Another object ofthe invention is to provide a method of making such a spunbond nonwovenlaminate.

SUMMARY OF THE INVENTION

To attain these objects, the invention is a spunbond nonwoven laminatehaving a plurality of spunbond nonwoven layers one atop the other, atleast two of the spunbond nonwoven layers with crimped continuousfilaments consisting or substantially consisting of crimped continuousfilaments, wherein

a first spunbond nonwoven layer having crimped multicomponent filamentsor crimped bicomponent filaments is provided formed by

-   -   a first component on the outer surface of the filaments of the        first layer consisting or substantially consisting of at least        one polyolefin, in particular of polyethylene, and    -   a second component of the filaments of the first layer        consisting or substantially consisting of a plastic having a        higher melting point than the polyolefin or polyethylene of the        first component of the filaments of the first layer,

the spunbond nonwoven laminate has a second outermost spunbond nonwovenlayer having multicomponent or bicomponent filaments, particularlyhaving crimped multicomponent or bicomponent filaments as a cover layerand formed by

-   -   a first component made of at least one polyolefin, in particular        polyethylene, on the outer surface of the filaments of the        second layer, consisting or substantially consisting of        polyethylene and    -   a second component of the filaments of the second layer        consisting or substantially consisting of a plastic having a        higher melting point than the polyolefin or polyethylene of the        first component of the filaments of the second layer, the        polyolefin portion or polyethylene portion of the first        component of the filaments of the second layer being higher than        the polyolefin portion or polyethylene portion of the first        component of the filaments of the first layer.

If “substantially consists” is specified here or below relative to aplastic or relative to a polymer, this means in particular that thepolymer is present in at least 95% by weight, preferably at least 97% byweight, and preferably also at least 98% by weight. The remaining % byweight can be formed in particular by additives such as plasticizers,fillers, colorants, and the like.

According to the invention, the spunbond nonwoven laminate has at leasttwo spunbond nonwoven layers having crimped continuous filaments.According to a recommended embodiment of the invention, a maximum offour spunbond nonwoven layers having crimped continuous filaments arepresent in the spunbond nonwoven laminate according to the invention.According to a particularly preferred embodiment of the invention, boththe first spunbond nonwoven layer and the second spunbond nonwoven layerhave crimped multicomponent filaments or crimped bicomponent filaments.It is within the scope of the invention that the first spunbond nonwovenlayer consists or substantially consists of crimped multicomponentfilaments or crimped bicomponent filaments. Furthermore, it is withinthe scope of the invention that the second outermost spunbond nonwovenlayer consists or substantially consists of crimped multicomponentfilaments or of crimped bicomponent filaments.

According to the invention, crimped continuous filaments are used in thefirst layer and preferably also in the further second layer of thespunbond nonwoven laminate according to the invention. The continuousfilaments expediently have a crimp with at least 1.5, preferably with atleast 2.5 and preferably with at least 3 loops per centimeter of theirlength. A crimp with 1.5 to 3.5, preferably from 1.8 to 3.2 andpreferably from 2 to 3 loops per centimeter of the length of thecontinuous filaments is particularly preferred here. The number of crimploops and/or crimp bows (loops) per cm length of the continuousfilaments is measured in particular according to the Japanese standardJIS L-1015-1981, by counting the crimps under a pretension of 2 mg/denin ( 1/10 mm), based on the unstretched length of the filaments. Asensitivity of 0.05 mm is used to determine the number of crimp loops.The measurement is expediently carried out using a “Favimat” apparatusfrom TexTechno, Germany. For this purpose, reference is made to thepublication “Automatic Crimp Measurement on Staple Fibers,” DenkendorfColloqium, “Textile Mess- and Prüftechnik,” Nov. 9, 1999, Dr. UlrichMörschel (in particular page 4, FIG. 4). For this purpose, the filamentsor the filament sample are/is removed as a filament ball from thedeposit or from the deposit mesh belt before further solidification, andthe filaments are separated and measured.

According to a recommended embodiment, the degree of crimp of thefilaments of the second layer of the laminate is equal to or less thanthe degree of crimp of the filaments of the first layer. This embodimenthas proven to be particularly advantageous with regard to attaining theobject of the invention.

A very recommended embodiment, which is of particular importance in thescope of the invention, is characterized in that the titer of thefilaments of the second layer (cover layer) is lower than the titer ofthe filaments of the first layer. It is recommended that the filamentsof the first layer have a titer of more than 1.5 den, preferably of morethan 1.6 den and preferably of more than 1.7 den. According to apreferred embodiment of the invention, the titer of the filaments of thefirst layer of the spunbond nonwoven laminate according to the inventionis between 1.5 den and 2.5 den, in particular between 1.6 den and 2.4den, preferably between 1.7 den and 2.3 den, very preferably between 1.8den and 2.2 den, and particularly preferably between 2.0 den to 2.2 den.It is within the scope of the invention that the filaments of the secondlayer have a titer of less than 1.7 den, in particular less than 1.6den, and, according to a recommended embodiment, a titer of 0.8 up to1.6 den, in particular from 0.9 den to 1.5 den, and preferably from 1.0den to 1.3 den. According to a further embodiment of the invention,filaments with a titer of up to 12 den can be used for the first layer.The filaments of the second layer then have a titer of, for example,less than 6 den or 6 den.

It has already been pointed out that, according to a preferredembodiment of the invention, the titer of the filaments of the secondoutermost layer is lower than the titer of the filaments of the firstlayer. The difference between the titer of the filaments of the firstlayer and the titer of the filaments of the second layer is preferablyat least 0.2 den, preferably at least 0.3 den, and recommended at most1.1 den, preferably at most 1.0 den. According to a further embodiment,the difference between the titer of the first layer and the titer of thesecond layer can be a maximum of 4 den to 6 den. The titer gradientprovided according to a preferred embodiment is particularlyadvantageous in terms of attaining the object of the invention.

The invention is based on the discovery that the spunbond nonwovenlaminate according to the invention is a product having high softnessand large volume or thickness that nevertheless fulfills allrequirements with regard to the strength properties. Above all, thespunbond nonwoven laminate according to the invention has excellentresistance to abrasion and, in this respect, optimal abrasionresistance. The tensile strength in the machine direction (MD) also hasvery good values, so that the laminate is easy to handle and use. It isparticularly important in the scope of the invention that the spunbondnonwoven laminate according to the invention is distinguished by anoptimally closed, homogeneous surface. The second layer of the laminateused as the cover layer contributes in particular to this. An excellentsurface uniformity of the laminate is achieved and disturbing elevationsfrom the surface or disturbing indentations in the surface can beeffectively avoided. At the same time, the laminate surface is not toorough and has optimal sliding properties. It should also be emphasizedthat the spunbond nonwoven laminate according to the invention can bemade without problems at high production speeds and can therefore bemade highly productively in a two-beam system or multibeam system. Thespunbond nonwoven laminate is characterized by homogeneous depositionand a homogeneous surface, and without any disturbing filamentagglomerates that arise in particular from the disadvantageous so-calledblow-back effects. It must also be added that the spunbond nonwovenlaminate according to the invention can be made in a simple andinexpensive manner and therefore in a cost-effective manner.

The invention is characterized in that a first component on the outersurface of the filaments of the first layer consists or substantiallyconsists of at least one polyolefin and in particular consists of orsubstantially consists of polyethylene. Above all, polypropylene canalso be used as the polyolefin. It is within the scope of the inventionthat the first component made of a polyolefin provided on the outersurface of the filaments of the first layer has a lower melting pointthan the second component or than the further component of the filamentsof the first layer.

A particularly preferred embodiment of the invention is characterized inthat the polyolefin portion or the polyethylene portion of the filamentsof the first layer is less than 40% by weight, in particular less than38% by weight, and preferably less than 35% by weight. It has alreadybeen pointed out that the polyolefin of the first component of thefilaments of the first layer is preferably polyethylene. It isrecommended that the melt flow rate (MFR) of this polyethylene is lessthan 35 g/10 min, in particular less than 30 g/10 min, preferably lessthan 25 g/10 min, and very preferably less than 20 g/10 min. If meltflow rates (MFR) are given here and below, these are measured forpolypropylene in particular according to ASTM D1238-13 (condition B,2.16 kg, 230° C.) and for polyethylene according to ASTM D1238-13 at190° C./2, 16 kg.

A preferred embodiment of the invention is characterized in that the atleast one further component or the second component of the filaments ofthe first layer consists or substantially consists of polypropylene or apolyester. For this further/second component, at least one polypropylenecopolymer can also be used instead of polypropylene or in addition topolypropylene and at least one polyester copolymer can also be usedinstead of the polyester or in addition to the polyester. Polyethyleneterephthalate (PET) is particularly suitable as a polyester and PETcopolymer (Co-PET) is particularly suitable as a polyester copolymer.However, polybutylene terephthalate (PBT) or polylactide (PLA) can alsobe used as polyester. Copolymers of these plastics can also be used. Arecommended embodiment of the invention is characterized in that the atleast one further component or the second component of the filaments ofthe first layer made of at least one plastic consists or substantiallyconsists of the group “polypropylene, polypropylene copolymer,polyethylene terephthalate (PET), PET copolymer, polybutyleneterephthalate (PBT), PBT copolymer, polylactide (PLA), PLA copolymer.” Aparticularly preferred embodiment is characterized in that the first, inparticular lower melting, component of the filaments of the first layerconsists or substantially consists of polyethylene and that the second,in particular higher melting component, of the filaments of the firstlayer consists or substantially consists of polypropylene. Anotherembodiment is characterized in that the first, in particular lowermelting, component of the filaments of the first layer consists orsubstantially consists of polypropylene or polyethylene and that thesecond, in particular higher melting, component of the filaments of thefirst layer consists or substantially consists of a polyester and/or ofa polyester copolymer. It is also within the scope of the invention thatmixtures or blends of the polymers mentioned are used for the componentsof the filaments of the first layer.

According to a particularly preferred embodiment of the invention, themulticomponent filaments or the bicomponent filaments of the first layerhave an eccentric core-sheath configuration. This embodiment has provenparticularly useful with regard to attaining the object of theinvention. A very recommended embodiment in this context ischaracterized in that the sheath of the filaments of the first layerhaving an eccentric core-sheath configuration has a constant thickness dor a substantially constant thickness d over at least 20%, in particularover at least 30%, preferably over at least 40%, preferably over atleast 50%, and very preferably over at least 60% and particularlypreferably over at least 65% of the filament circumference. Here andbelow, the thickness d means in particular the average thickness d. Thisparticularly preferred embodiment is explained in more detail below.

If, according to a highly recommended embodiment, the filaments of thefirst layer have an eccentric core-sheath configuration, it is withinthe scope of the invention that the lower-melting first component isprovided in the sheath of the filaments and the higher-melting at leastone second component or the higher melting second component is presentin the core of the filaments. According to a first embodiment of theinvention, the multicomponent or bicomponent filaments of the firstlayer have an eccentric core-sheath configuration, the sheath consistingor substantially consisting of polyethylene or of polyethylene and thecore consisting or substantially consisting of polypropylene orpolypropylene copolymer. According to a second embodiment, themulticomponent or bicomponent filaments of the first layer have aneccentric core-sheath configuration, the sheath consisting orsubstantially consisting of a polyolefin and/or polyolefin copolymer, inparticular of polypropylene and/or polypropylene copolymer, and whereinthe core consists or substantially consists of a polyester and/or apolyester copolymer, in particular of polyethylene terephthalate (PET)and/or PET copolymer. The eccentric core-sheath configuration describedabove with a constant sheath thickness d is particularly preferred.

If the second component of the filaments of the first layer consists orsubstantially consists of polypropylene and/or polypropylene copolymer,the polypropylene or the polypropylene copolymer expediently has a meltflow rate (MFR) of more than 25 g/10 min, in particular more than 30g/10 min, preferably more than 45 g/10 min, preferably more than 55 g/10min, and particularly preferably more than 60 g/10 min. The melt flowrate (MFR) of the polypropylene or the polypropylene copolymer can beadjusted by additives, in particular by polymer additives, peroxide orthe like.

According to the invention, at least a first layer or a first componenton the outer surface of the filaments of the second layer (cover layer)consists or substantially consists of at least one polyolefin, inparticular polyethylene. According to the invention, this proportion ofpolyolefin or polyethylene of the first component of the filaments ofthe second layer is greater than the polyolefin portion or polyethyleneportion of the first component of the filaments of the first layer. Thepolyolefin portion, in particular the polyethylene portion of thefilaments of the second layer, is preferably more than 33% by weight,suitably more than 35% by weight, and preferably more than 38% byweight. An embodiment of the invention is characterized in that thepolyolefin portion, in particular the polyethylene portion of thefilaments of the second layer, is preferably 38% by weight to 67% byweight, in particular 40% by weight to 65% by weight, and preferably 40%by weight to 60% by weight. It is recommended that these weightpercentages relate to the lower melting first component of the filamentsof the second layer.

A recommended embodiment of the invention is characterized in that thefirst component on the outer surface of the filaments of the secondlayer consists of polyethylene or substantially consists ofpolyethylene. The melt flow rate (MFR) of this polyethylene isexpediently greater than 15 g/10 min, in particular greater than 20 g/10min and preferably greater than 27 g/10 min. If, according to apreferred embodiment of the invention, the first component on the outersurface of the filaments of both layers consists or substantiallyconsists of polyethylene, the melt flow rate of the polyethylene of thefilaments of the second layer is expediently greater than the melt flowrate of the polyethylene of the filaments of the first layer.

According to the invention, the at least one further or a secondcomponent of the filaments of the second layer consists or substantiallyconsists of a plastic having a higher melting point than the polyolefinor than the polyethylene of the first component of the filaments of thesecond layer. A particularly preferred embodiment of the invention ischaracterized in that the at least one further or the second componentof the filaments of the second layer consists or substantially consistsof polypropylene and/or polypropylene copolymer. In principle, thiscomponent can also consist or substantially consist of at least onepolyester and/or polyester copolymer. For this purpose, the polyestersor polyester copolymers specified above for the second component of thefilaments of the first layer can preferably be used.

If, according to a preferred embodiment, polypropylene is used for thesecond component of the filaments of the second layer, the melt flowrate (MFR) of this polypropylene of the second component of the secondlayer is preferably more than 25 g/10 min and in particular more than 50g/10 min. It is within the scope of the invention that themulticomponent filaments or the bicomponent filaments of the secondlayer have an eccentric core-sheath configuration or a side-by-sideconfiguration. An eccentric core-sheath configuration of these filamentsis particularly preferred. A very particularly recommended embodiment ofthe invention is characterized in that the multicomponent filaments orthe bicomponent filaments of the second layer have an eccentriccore-sheath configuration and that the sheath of the filaments has aconstant thickness d or a substantially constant thickness d over atleast 20%, in particular over at least 30%, preferably over at least40%, preferably over at least 50%, and very preferably over at least 60%and particularly preferably over at least 65% of the filamentcircumference.

The invention is based on the discovery that the second layer (coverlayer or cover layer) of the spunbond nonwoven laminate according to theinvention is responsible, in particular, for the homogeneous surfaceproperties of the laminate. The features of this second layer accordingto the invention require a high degree of softness and sufficientstrength as well as a closed surface. This second layer (cover layer)particularly preferably forms the outer surface of the product when thespunbond nonwoven laminate according to the invention is used in aproduct. This second layer or surface layer meets all requirements froman aesthetic point of view and contributes to the spunbond nonwovenlaminate having excellent opacity. In particular, the second layerforming the cover layer has very homogeneous surface properties withoutdefect sites and above all without disruptive agglomerates.

According to a particularly preferred embodiment of the invention, thefirst layer and the second layer of the spunbond nonwoven laminateaccording to the invention are provided directly on top of one anotherwithout the interposition of further layers or layers. According toanother embodiment, further layers or layers, for example furtherspunbond nonwoven layers and/or meltblown nonwoven layers, can also beinterposed between the first and the second layer.

According to a recommended embodiment of the invention, the basis weightof the second layer is less than the basis weight of the first layer.The basis weight of the first layer is preferably greater than the basisweight of the second layer by at least a factor of 1.1, in particular atleast by a factor of 1.2, and preferably at least by a factor of 1.25.It is within the scope of the invention that the basis weight of the(total) spunbond nonwoven laminate is less than 40 g/m².

A particularly preferred embodiment of the invention is characterized inthat the strength of the spunbond nonwoven laminate in the machinedirection (MD) is greater than 25 N/5 cm. The thickness of the spunbondnonwoven laminate is expediently more than 0.50 mm, in particular morethan 0.53 mm, preferably more than 0.55 mm, and particularly preferablymore than 0.58 mm. The strength and thickness values given above applyin particular to spunbond nonwoven laminates with a basis weight of 12to 50 g/m², preferably 20 to 30 g/m².

According to the invention, the at least two layers of the spunbondnonwoven laminate according to the invention are made as spunbondnonwoven layers. It is within the scope of the invention that each ofthe at least two nonwoven layers is made with a spunbonding device orwith a spunbonding beam. In this respect, at least one two-beam systemhaving two spunbonding devices is required to produce the spunbondnonwoven laminate according to the invention. It is within the scope ofthe invention that each spunbonding device has a spinning apparatus orspinneret as well as a cooler downstream of the spinneret and at leastone stretcher downstream of the cooler. At least one diffuser ispreferably provided downstream of the stretcher. A very particularlyrecommended embodiment of the invention is characterized in that theassembly of the cooler and the stretcher is designed as a closedsubassembly and that, apart from the supply of cooling air to thecooler, there is no further external air supply to this assembly. Thecontinuous filaments leaving the diffuser or the last diffuser in theflow direction of the filaments are expediently deposited on a depositconveyor or in particular on a deposit mesh belt. The preconsolidationof each nonwoven layer or spunbond nonwoven layer is then preferablycarried out on the deposit conveyor or on the deposit mesh belt.

A particularly recommended embodiment of the invention is characterizedin that at least one of the two layers of the spunbond nonwoven laminateis preconsolidated with hot air from above and in particular is onlypreconsolidated with hot air. An embodiment in which the at least twolayers of the spunbond nonwoven laminate according to the invention arepreconsolidated with hot air or both layers are only preconsolidatedwith hot air has proven particularly useful in the scope of theinvention. It is also within the scope of the invention that the finalconsolidation of the spunbond nonwoven laminate takes place with hot airand, according to one embodiment of the invention, takes place only withhot air. The spunbond nonwoven laminate is then a spunbond nonwovenlaminate that is only preconsolidated and finally consolidated with hotair. This embodiment is of particular importance in the scope of theinvention.

A proven embodiment of the invention is characterized in that at leastone layer, preferably both layers, of the spunbond nonwoven laminateaccording to the invention are each preconsolidated at a temperaturebelow 150° C., in particular at a temperature below 140° C., andpreferably at a temperature below 135° C. It is particularly preferredwithin the scope of the invention that at least one layer, preferablyboth layers, of the spunbond nonwoven laminate is preconsolidated with ahot air knife and/or with a hot air oven. According to one embodimentvariant, the hot air knife forms the first preconsolidater in the traveldirection of the layer and then the hot air oven forms the secondpreconsolidater downstream in the travel direction of the layer.Basically, only a hot air knife or just a hot air oven can be used forthe preconsolidation of a layer of the spunbond nonwoven laminate. It isalso possible that the first preconsolidater is formed by the hot airoven and the second preconsolidater downstream in the travel directionis formed by the hot air knife. The spunbond nonwoven according to theinvention is expediently finally consolidated by hot air and preferablyfinally consolidated in a hot air oven.

An embodiment that is of particular importance in the scope of theinvention is characterized in that the second layer (cover layer) of thespunbond nonwoven laminate according to the invention is made by meansof a spunbonding device and is first deposited on the deposit conveyoror on the deposit mesh belt, and after that the first layer is made witha spunbonding device and is applied to the second layer (cover layer)already deposited on the deposit conveyor or on the deposit mesh belt.It has been shown that particularly advantageous products or spunbondnonwoven laminates are obtained in this way.

To attain the inventive object, the invention further teaches a methodof making a spunbond nonwoven laminate having a plurality of spunbondnonwoven layers one atop the other, at least two of the spunbondnonwoven layers having crimped continuous filaments or consisting orconsisting substantially of crimped continuous filaments, wherein

a first spunbond nonwoven layer having crimped multicomponent orbicomponent filaments is made, and at least one first component on theouter surface of the filaments of the first layer consists orsubstantially consists of at least one polyolefin, in particular ofpolyethylene, while at least one further or a second component of thefilaments of the first layer consists or substantially consists of aplastic having a higher melting point than the polyolefin orpolyethylene of the first component of the filaments of the first layer,

the first layer is preconsolidated, preferably preconsolidated with hotair, in particular only preconsolidated with hot air,

a second outermost spunbond nonwoven layer is made with multicomponentor bicomponent filaments, especially with crimped multicomponent orbicomponent filaments as a cover layer, and at least one first componentmade of at least one polyolefin, in particular, on the outer surface ofthe filaments of the second layer consists or substantially consists ofpolyethylene, while at least one further or a second component of thefilaments of the second layer consists or substantially consists of aplastic having a higher melting point than the polyolefin orpolyethylene of the first component of the filaments of the secondlayer,

the second spunbond nonwoven layer is preconsolidated, preferablypreconsolidated with hot air, in particular is only preconsolidated withhot air,

the polyolefin portion or polyethylene portion of the first component ofthe filaments of the second layer is greater than the polyolefin portionor polyethylene portion of the first component of the filaments of thefirst layer, and

the spunbond nonwoven laminate is finally consolidated, preferably isfinally consolidated with hot air, in particular is only finallyconsolidated with hot air.

A particularly recommended embodiment of the method according to theinvention is characterized in that the second outermost spunbondnonwoven layer is first made or deposited on a conveyor and then ispreconsolidated, preferably is preconsolidated with hot air and inparticular is only preconsolidated with hot air, and

the first layer is then generated and deposited on the second layeralready deposited, the second layer or the aggregate from the first andsecond layers then being preconsolidated, preferably preconsolidatedwith hot air, and in particular only preconsolidated with hot air, and

the spunbond nonwoven laminate is finally consolidated, preferablyfinally consolidated with hot air, and in particular is finally onlyconsolidated with hot air.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is a vertical section through an apparatus for making a layer ofa spunbond nonwoven laminate according to the invention;

FIG. 2 is a schematic side view of a two-beam system with twospunbonding devices for making two layers of a spunbond nonwovenlaminate according to the invention;

FIG. 3 is a section through a spunbond nonwoven laminate according tothe invention; and

FIG. 4 is a section through a continuous filament preferably usedaccording to the invention with an eccentric core-sheath configuration.

SPECIFIC DESCRIPTION OF THE INVENTION

FIG. 1 shows a spunbonding device for making a spunbond nonwoven layer 2or 3 for an inventive spunbond nonwoven laminate 1. Such a spunbondnonwoven layer 2 or 3 made with the apparatus has crimped continuousfilaments F or consists of crimped continuous filaments F, orsubstantially consists of crimped continuous filaments F. It is withinthe scope of the invention that the continuous filaments F arethermoplastic.

The apparatus shown in FIG. 1 comprises a spinneret 10 for spinning thecontinuous filaments F and these spun continuous filaments F areexpediently introduced into a cooler 11 with a cooling chamber 12.Preferably, air supply manifolds 13 and 14 are one atop the other on twoopposite sides of the cooling chamber 12. Air of different temperaturesis expediently introduced into the cooling chambers from these airsupply manifolds 13 and 14. As recommended, a monomer extractor 15 isprovided between the spinneret 10 and the cooler 11. With this monomerextractor 15, disruptive gases occurring during the spinning process canbe removed from the apparatus. These gases can be, for example,monomers, oligomers, or decomposition products and the like substances.

The cooler 11 preferably and, in the embodiment in the filament flowdirection, is followed by a stretcher 16 for stretching the continuousfilaments F. Preferably, the stretcher 16 has an intermediate passage 17that connects the cooler 11 to a stretching shaft 18 of the stretcher16. According to a particularly preferred embodiment, the assembly fromthe cooler 11 and the stretcher 16 or the assembly from the cooler 11,the intermediate passage 17, and the stretching shaft 18 is designed asa closed subassembly and, apart from the supply of cooling air in thecooler 11, there is no further air supply from outside in thisaggregate.

The stretcher 16 is preferably in this embodiment in the filament flowdirection by a diffuser 19 through which the continuous filaments F arepassed. After passing through the diffuser 19, the continuous filamentsF are preferably, deposited on a conveyor designed as a deposit meshbelt 20. The deposit mesh belt 20 is preferred and, in the embodiment,is designed as an endlessly rotating deposit mesh belt 20. This depositmesh belt 20 is expediently air-permeable so that process air can beaspirated from below through the deposit mesh belt 20.

Preferably, the diffuser 19 has two lower diverging upstream anddownstream diffuser walls 21 and 22. These diverging diffuser walls 21and 22 are expediently asymmetrical with respect to the center plane Mof the apparatus or the diffuser 19. As recommended, the upstreamdiffuser wall 21 forms a smaller angle β with the center plane M thanthe downstream diffuser wall 22. The angle β that the upstream diffuserwall 21 forms with the center plane M is recommended to be at least 1°smaller than the angle β that the downstream diffuser wall 22 forms withthe center plane M.

It is within the scope of the invention that two opposite secondary airinlet gaps 24 and 25 are provided at the inflow end 23 of the diffuser19, each of which is formed in part by a respective one of the twoopposite diffuser walls. A smaller secondary air volume flow canpreferably be introduced through the upstream secondary air inlet gap 24than through the downstream secondary air inlet gap 25. It isrecommended that the secondary air volume flow of the upstream secondaryair inlet gap 24 is at least 5%, preferably at least 10% and inparticular at least 15% lower than the secondary air volume flow throughthe downstream secondary air inlet gap 2.

FIG. 2 shows a two-beam system with two spunbonding devicescorresponding to FIG. 1 for making two spunbond nonwoven layers 2 and 3to form a spunbond nonwoven laminate 1 according to the invention. Forthe sake of simplicity, the apparatus components of the spunbondingdevices have not been shown in full in FIG. 2, but only the lower regionof the respective diffusers 19. According to a particularly preferredembodiment, continuous filaments F are first spun with the upstreamspunbonding device for the two-beam system and deposited to form thesecond spunbond nonwoven layer 3 (cover layer). Continuous filaments Ffor the first spunbond nonwoven layer 2 are then spun with thespunbonding device downstream in the travel direction of the depositmesh belt 20 on the right in FIG. 2 and deposited on the deposit meshbelt 20 or on the second spunbond nonwoven layer 3. This order ofproduction of the spunbond nonwoven layers 2, 3 is particularlyrecommended in the scope of the invention.

Below the deposit region 26 for the continuous filaments F of eachspunbonding device, process air is extracted through the deposit meshbelt 20 in a main suction area 27, with a suction velocity v_(H). Thenonwoven layer [2,] 3 made with the first spunbonding device shown onthe left in FIG. 2, preferably and here the second layer 3, isrecommended to be supplied to the hot-air preconsolidaters with thedeposit mesh belt 20. Preferably, this second layer 3 is firstpreconsolidated with a hot air knife 31 and then preferably furtherconsolidated with a hot air oven 32 connected downstream in the machinedirection (MD). In the recommended embodiment, process air is extractedby the deposit mesh belt 20 both below the hot air knife 31 and belowthe hot air oven 32, specifically in the case of the hot air knife 31with a suction velocity v₂ and in the case of the hot air oven with asuction velocity v₃. For the suction velocities, it is preferably thecase that the suction velocity v_(H) is greatest in the main suctionarea 27 and the suction velocity v₂ under the hot air knife 31 is thesecond largest and that the suction velocity v₃ under the hot air oven32 is the third largest. The suction velocity v thus decreases from thedeposit region 26 of the filaments F to the hot air oven 32. The hot airknife 31 (left in FIG. 2) preferably preconsolidates the second layer 3at a hot air temperature of 80° C. to 250° C., preferably at 120° C. to190° C. The hot-air preconsolidation in the downstream hot air oven 32is advantageously carried out at a hot air temperature of 110° C. to180° C., preferably from 120° C. to 160° C. The hot air knife 31 (leftin FIG. 2) is preferred and, in the embodiment, hot air is supplied at ahigher speed than the hot air of the downstream hot air oven 32. Thespeed of the supplied hot air in the hot air knife 31 preferably has aspeed that is greater by at least a factor of 1.5, preferably a factorof 1.8, than the speed of the hot air in the hot air oven 32.Furthermore, as recommended, the width in the machine direction (MD) inwhich hot air is applied is narrower for the first (in FIG. 2 left) hotair knife 31 than for the first (in FIG. 2 left) hot air oven 32. Thewidth of the hot air exposure in the machine direction (MD) in the hotair oven 32 is larger by at least a factor of 1.5 than in the hot airknife 31.

A second spunbond nonwoven layer 2, 3, preferably and here the firstlayer 2, for the spunbond nonwoven laminate 1 is made with the rightsecond spunbonding device shown in FIG. 2. This first layer 2 isrecommended and, in the embodiment, deposited on the second spunbondnonwoven layer 3 already transported by the deposit mesh belt 20.Subsequently, it is preferred and here the aggregate from two layers 2,3 is preconsolidated, specifically as recommended and herepreconsolidated with hot air. For this purpose, a hot air knife 31 isfirst downstream of the second spunbonding device in the machinedirection (MD) and a hot air oven 32 is in turn downstream of the hotair knife 31. In the case of the second spunbonding device and in theaforementioned hot-air preconsolidaters of the second spunbondingdevice, the suction operations explained for the first spunbondingdevice are expediently carried out with the corresponding suctionvelocities. The parameters mentioned there for the hot-airpreconsolidaters, in particular temperatures and width parameters, alsoapply to the hot air knife 31 and to the hot air oven 32 behind thesecond spunbonding device. In the embodiment of FIG. 2, both layers 2, 3of the spunbond nonwoven laminate 1 according to the invention are onlypreconsolidated with hot air.

It is within the scope of the invention that the preconsolidatedaggregate from the two layers 2 and 3 is then finally consolidated, andis preferably finally consolidated by means of hot air. For thispurpose, a hot air oven, not shown in the figures, is expediently used.According to one embodiment of the invention, the layers or the twolayers 2, 3 of the spunbond nonwoven laminate 1 are both preconsolidatedwith hot air or only preconsolidated with hot air and also finallyconsolidated with hot air or only finally consolidated with hot air.

FIG. 3 schematically shows a section through an inventive spunbondnonwoven laminate 1 with the two layers 2 and 3.

FIG. 4 shows bicomponent filaments with an eccentric core-sheathconfiguration, which are very particularly preferred for the layers 2, 3of the spunbond nonwoven laminate 1 according to the invention.According to one embodiment of the invention, both layers 2, 3 of thespunbond nonwoven laminate 1 consist of such bicomponent filaments withan eccentric core-sheath configuration. FIG. 4 shows a cross sectionthrough a continuous filament F with the preferred special core-sheathconfiguration. With these continuous filaments F, the sheath 37preferably has a constant thickness d in the filament cross section andhere over more than 50%, preferably over more than 55% of the filamentcircumference. Preferably, the core 4 of the filaments F takes up morethan 65% of the area of the filament cross section of the filaments F.As recommended, the core 4, seen in the filament cross section, isdesigned in the shape of a segment of a circle. Expediently, this core 4has an arcuate peripheral portion 5 and a secantal peripheral portion 6with regard to its circumference. Preferably, the arcuate peripheralportion of the core 4 takes up over 50%, preferably over 55% of thecircumference of the core 4. Expediently, the sheath 37 of the filamentsF, seen in the filament cross section, is formed in the shape of asegment of a circle outside the sheath region with a constant thicknessd. This circular segment 7 of the sheath 37 has, as recommended, anarcuate peripheral portion 8 and a straight peripheral portion 9 withregard to its circumference. The thickness d or the average thickness dof the sheath 37 in the region of its constant thickness is preferably0.5% to 8%, in particular 2% to 10% of the filament diameter D. Thethickness d or the average thickness d of the sheath is preferably 0.1μm to 3 μm. FIG. 4 also shows the distance a of the center of gravity ofthe core 4 from the centroid of the sheath 3 of the continuous filament2. The distance a between the centroid of the core 4 and the centroid ofthe sheath 3 is preferably 5% to 40% of the filament diameter D or thelargest filament diameter D for the filaments F here.

1. A spunbond nonwoven laminate comprising: a first spunbond nonwovenlayer having crimped multicomponent or bicomponent filaments formed by afirst component on an outer surface of the filaments of the first layerconsisting or substantially consisting of a polyolefin, and a secondcomponent consisting or substantially consisting of a plastic having ahigher melting point than the polyolefin of the first component of thefilaments of the first layer; and a second outermost spunbond nonwovenlayer on the first layer having multicomponent or bicomponent filamentsas a cover layer and formed by a first component on an outer surface ofthe filaments of the second layer consisting or substantially consistingof a polyolefin, and a second component consisting or substantiallyconsisting of a plastic having a higher melting point than thepolyolefin of the first component of the filaments of the second layer,a polyolefin portion of the first component of the filaments of thesecond layer being greater than a polyolefin portion of the firstcomponent of the filaments of the first layer.
 2. The spunbond nonwovenlaminate according to claim 1, wherein a titer of the filaments of thesecond outermost layer is less than a titer of the filaments of thefirst layer.
 3. The spunbond nonwoven laminate according to claim 1,wherein the second component of the filaments of the first layerconsists or substantially consists of polypropylene or polyester.
 4. Thespunbond nonwoven laminate according to claim 1, wherein the polyolefinportion of the filaments of the first layer is less than 40% by weight.5. The spunbond nonwoven laminate according to claim 1, wherein thefilaments of the first layer have a titer of more than 1.5 den, and thefilaments of the first layer according to the recommended embodimenthave a titer of 1.5 den to 2.5 den.
 6. The spunbond nonwoven laminateaccording to claim 1, wherein the multicomponent or bicomponentfilaments of the first layer have an eccentric core-sheathconfiguration.
 7. The spunbond nonwoven laminate according to claim 6,wherein the sheath of the filaments of the first layer having aneccentric core-sheath configuration is at least 20% of a circumferencethe filament and has a substantially constant thickness d.
 8. Thespunbond nonwoven laminate according to claim 1, wherein the polyolefinof the first component of the filaments of the first layer ispolyethylene having a melt flow rate of less than 35 g/10 min.
 9. Thespunbond nonwoven laminate according to claim 1, wherein the secondcomponent of the filaments of the first layer consists or substantiallyconsists of polypropylene having a melt flow rate of more than 25 g/10min.
 10. The spunbond nonwoven laminate according to claim 1, whereinthe multicomponent or bicomponent filaments of the second spunbondnonwoven layer are crimped filaments.
 11. The spunbond nonwoven laminateaccording to claim 1, wherein the second component of the filaments ofthe second layer consists or substantially consists of polypropylene.12. The spunbond nonwoven laminate according to claim 1, wherein thepolyolefin portion of the filaments of the second layer is more than 33wt.-%, and the polyolefin portion is preferably 40 wt.-% to 65 wt.-%.13. The spunbond nonwoven laminate according to claim 1, wherein thefilaments of the second layer have a titer of less than 1.7 den.
 14. Thespunbond nonwoven laminate according to claim 1, wherein themulticomponent or bicomponent filaments of the second layer have aneccentric core-sheath configuration or a side-by-side configuration. 15.The spunbond nonwoven laminate according to claim 1, wherein themulticomponent filaments or the bicomponent filaments of the secondlayer have an eccentric core-sheath configuration and the sheaths of thefilaments have a constant thickness d or a substantially constantthickness d over at least 20% of a filament circumference.
 16. Thespunbond nonwoven laminate according to claim 1, wherein the firstcomponent on the outer surface of the filaments of the second layerconsists or substantially consists of polyethylene having a melt-flowrate greater than 15 g/10 min.
 17. The spunbond nonwoven laminateaccording to claim 11, wherein the melt flow rate of the polypropyleneof the second component of the second layer is more than 25 g/10 min.18. The spunbond nonwoven laminate according to claim 1, wherein adegree of crimp of the filaments of the second layer is equal to or lessthan a degree of crimp of the filaments of the first layer.
 19. Thespunbond nonwoven laminate according to claim 1, wherein a weight perunit area of the second layer is less than a weight per unit area of thefirst layer.
 20. The spunbond nonwoven laminate according to claim 1,wherein a basis weight of the spunbond nonwoven laminate is less than 30g/m².
 21. The spunbond laminate according to claim 1, wherein a strengthof the spunbond nonwoven laminate in a machine direction is greater than25 N/5 cm, the spunbond nonwoven laminate in particular having a basisweight of 12 to 50 g/m².
 22. The spunbond laminate according to claim 1,wherein a thickness of the spunbond nonwoven laminate is more than 0.50mm, and the spunbond nonwoven laminate has in particular a basis weightfrom 12 to 50 g/m².
 23. The spunbond nonwoven laminate according toclaim 1, wherein a difference between a titer of the filaments of thefirst layer and a titer of the filaments of the second layer is at least0.2 den.
 24. A method of making a spunbond nonwoven laminate, the methodcomprising the steps of: providing a first spunbond nonwoven layerhaving crimped multicomponent or bicomponent filaments and formed by afirst component on an outer surface of the filaments of the first layerconsisting or substantially consisting of a polyolefin, and a secondcomponent consisting or substantially consisting of a plastic having ahigher melting point than the polyolefin of the first component of thefilaments of the first layer preconsolidating the first layer with hotair; providing a second outermost spunbond nonwoven layer havingmulticomponent or bicomponent filaments as a cover layer and formed by afirst component on an outer surface of the filaments of the second layerconsisting or substantially consisting of a polyolefin, and a secondcomponent consisting or substantially consisting of a plastic having ahigher melting point than the polyolefin of the first component of thefilaments of the second layer, a polyolefin portion of the firstcomponent of the filaments of the second layer being greater than apolyolefin portion of the first component of the filaments of the firstlayer; preconsolidating the second layer with hot air; and finallyconsolidating the spunbond nonwoven laminate formed by the first andsecond layers with hot air.
 25. The method according to claim 24,wherein first the second spunbond nonwoven layer is made as a coverlayer and is preconsolidated, and then the first spunbond nonwoven layeris formed on the second spunbond nonwoven layer is in turnpreconsolidated.
 26. The method according to claim 24, wherein crimpedmulticomponent or bicomponent filaments are used for the second spunbondnonwoven layer.